In monitoring systems for parking lots, it is very essential to be as flexible as possible with respect to the tariff. It should be possible to apply one tariff for week days, for example, and another for Saturdays, for Sundays or other holidays. It should also be possible to permit certain parking times to be free of charge and to leave a vehicle on the parking space over a longer time interval than originally set, nevertheless charging the owner of the vehicle with the correct fee in accordance with the tariff. Apart from that, of course, a plurality of coins should be usable. An additional requirement is that the supervising of the payment of the fees for each individual parking space should be as simple as possible and as inexpensive as possible. The user of the parking space, furthermore, wants to be relieved from having to make complicated calculations with respect to a table supplying the tariff data. After having inserted a coin, the user should also be able to read from the parking meter itself the amount of time for which he has paid his parking fees without having to make any calculations.
All known monitoring systems for parking spaces fulfill these demands to only a limited extent. Generally known mechanical curbside parking meters are not particularly usable for parking spaces since they are not very flexible in their tariff organization, especially when night and weekend tariffs and a longer prepayment interval have to be taken into consideration. Even if an intricate arrangement of scales and indicators, and corresponding control of the clockwork of such mainly mechanical parking meter were provided, the disadvantage remains that the user of the parking meter would be forced to make complicated calculations with respect to the parking time made available to him for the coins to be inserted employing the available tariff data before he arrives at the desired result.
Another known monitoring system for parking lots are the so-called ticket issuing devices. At a central spot within a parking area, for instance, on each deck of a parking house, such a ticket issuing device is installed. The vehicle owner has to walk to this device to insert his coins and to obtain the so-called ticket which shows the time of departure. By means of this ticket, the user must return to his vehicle and must place it behind the windshield so that it is visible from outside. It is understandable that such a ticket issuing device is only very reluctantly accepted by the users since users who are not subscribers in a certain parking lot do not generally know the parking area very well and therefore have to spend much time looking for the ticket issuing device to obtain this ticket and return therewith to the vehicle. Apart from that, due to its complexity, this system requires a lot of supervisory expense for the operator of the parking lot. Other examples for such ticket issuing devices are described, for example, in DE-Offenlegungsschrift 15 74 180.
In French Pat. No. 13 94 660, a monitoring system for parking spaces is disclosed, having a central control unit and individual parking meters attributed to the individual parking spaces. This system works on the electromechanical principle and payment is effected after use. The customer, after having placed his vehicle in the parking space, either by means of the vehicle itself or by any other manipulation which the driver has to make, sets the time and coin indicating device in motion. Fees do not have to be paid at the beginning but the parking space is automatically closed. During the parking time, by means of a central control unit, each individual parking meter is switched on in accordance with the time of day. Differing tariffs for day times and night times can be taken into consideration, so that varying tariffs in accordance with day or night times are possible. When the customer returns, he can read off the fee to be paid on the parking meter. He inserts the coins since only in this manner can he open the gate closing his parking space, so that he can drive away.
The just described system has two essential disadvantages. The payment-on-return system can only function in connection with gates or other closing means for the individual parking spaces. This, however, is a very expensive installation. Further, the electromechanical embodiment shown in the above-mentioned patent specification is not very flexible with respect to the tariff organization and allows only advance payments to a very limited extent for a longer period of time.